Cyclonic vacuum cleaners are well known in the art. Typically, a cyclonic vacuum uses a rigid cyclone container in place of a bag. The cyclone container typically is cylindrical or somewhat tapered, and includes an inlet that receives dirty air, and an outlet through which cleaned or partially-cleaned air exits. A vacuum fan is used to convey the air through the cyclone container, and the fan may be located upstream or downstream of the cyclone container. As the air passes through the cyclone container, it is directed in a cyclonic pattern to remove dirt and dust from the air flow due to the vortex motion of the cyclone. The removed dirt and dust is deposited with the lower portion of the container or directed into an auxiliary dirt collection container as it drops out of the cyclonic air flow.
It is also well known to use more than one cyclone in the air flow path, and multiple series and/or parallel cyclones may be used in a single vacuum cleaner. Further, filtration features, such as shrouds and other kinds of filter, may be used within the air flow path, either within the cyclone or cyclones, or upstream or downstream of them. For example, a shroud may be used to direct the air flow within the cylindrical container into a vortex, and to force the airflow to change directions to remove particles by inertia. Shrouds may come in various shapes and sizes, and it is known to provide cylindrical shrouds, conical shrouds, frustoconical shrouds, and shrouds having other shapes. Shrouds may be formed with a mesh type screen, circular perforations, or other apertures or openings to allow air to pass through the shroud while filtering out larger particles. Depending on the application, the perforations may be specifically sized to prevent certain size dust and dirt particles from passing through, while providing relatively little impediment to the airflow, and different hole geometries have been used in efforts to improve air/dirt separation within a vacuum cleaner.
It is also well known that cyclone shrouds may be provided in the form of microporous filters. Indeed, a shroud is simply a filter having large pores. Filters used in cyclones may comprise any of various useful types and shapes, such as pleated, foam, ultra fine, HEPA, ULPA, and so on. Combinations of shrouds and/or microporous filters having various filtration sizes may be used in any number of combinations within or in conjunction with a vacuum cleaner cyclone separator.
Cyclone shrouds and other kinds of filter also may have other features to enhance airflow or dirt separation. For example, a feature such as a flow reversing lip may be added to a shroud. Flow reversing lips typically are located circumferentially around the bottom lip of the shroud and extend downward, at an angle, or radially, to obstruct the airflow flowing from below the shroud up to the shroud surface. Such flow reversing lips may enhance dirt separation, prevent larger objects from being lifted into contact with the shroud's perforated surface, or provide other benefits. Exemplary cyclonic vacuums having shrouds, reversing lips, filters, and other filtration and flow controlling devices are described in U.S. Pat. Nos. 5,145,499; 5,893,936; 6,910,245; and 7,222,392, which references are incorporated herein.
While various prior art devices, such as those described above, have been used, there exits a need to provide alternatives to such devices.